This invention relates to improved monomeric and polymeric compositions derived from cyclobutarenes and the processes for preparing them.
Polymeric compositions derived from biscyclobutarene monomers are disclosed in U.S. Pat. No. 4,540,763. They are prepared by subjecting biscyclobutarene monomers to temperatures sufficient to polymerize the monomers. These compositions exhibit excellent thermal stability at high temperatures, good chemical resistance to most industrial solvents, and low sensitivity to water. These properties are highly desirable for applications in the electronics and aerospace industries, as well as for any other application where thermoset resins exhibiting outstanding physical and mechanical properties are required.
Thermoset resins are monomeric and polymeric compositions which can solidify irreversibly upon heating. They are useful in many engineering applications. For example, they are useful as coatings, structural laminates, adhesives, films, and composities. Typical thermoset resins exhibiting properties which encourage their use as engineering materials include polyesters, polyamides, polyimides, and epoxy resins.
Unfortunately, conventional thermoset resins do not exhibit the thermal stability, chemical resistance and low sensitivity to water of the polymeric compositions of U.S. Pat. Nos. 4,540,763 prepared from biscyclobutarene monomers. Therefore, it would be desirable to provide improved thermoset resins derived from cyclobutarenes that exhibit the properties required for demanding applications in the electronics and aerospace industries, as well as other industries where high performance is required. cl SUMMARY OF THE INVENTION
In one aspect, the invention represents a cyclobutarene ketoaniline monomer and the process for preparing it. The monomer is represented by the formula: ##STR2## wherein Ar is an aromatic moiety having one valence on each of two adjacent carbon atoms of an aromatic ring;
Ar.sup.1 is substituted or unsubstituted arylene; PA1 each R is independently hydrogen, a monovalent electron donating moiety or a monovalent electron withdrawing moiety; and PA1 each m and n is independently an integer of 1 or 2. PA1 Ar.sup.1 is substituted or unsubstituted arylene; PA1 each R is independently hydrogen, a monovalent electron donating moiety or a monovalent electron withdrawing moiety; and PA1 each m and n is independently an integer of 1 or 2. PA1 R.sup.1 is chloro, bromo, or iodo; and PA1 n is an integer of 1 or 2. PA1 m is a number between 0.5 and 0.99, inclusive; and PA1 n is a number between 0.01 and 0.5, inclusive.
The process for preparing the monomer comprises the steps of reacting a cyclobutarene with a nitro-substituted aromatic acid halide in the presence of a reaction catalyst capable of either accepting a pair of electrons or donating a proton during the reaction and then contacting the resulting cyclobutarene intermediate with a reducing agent at conditions sufficient to selectively reduce the nitro groups to amino groups.
In another aspect, the invention is a process for grafting and/or endcapping a monomer or polymer with a cyclobutarene moiety comprising the step of reacting either a monomer having at least 1 amino-reactive functionality or a polymer having at least one amino-reactive functionality with the monomer of this invention.
In yet another aspect, the invention is a process for preparing a crosslinked network from the grafted and/or endcapped monomers and polymers prepared from the process of this invention, comprising the step of subjecting the grafted and/or endcapped monomer or polymer to ring scission polymerization conditions.
In a final aspect, the invention is a process for preparing a homopolymer from the monomer of this invention, comprising the step of subjecting the monomer to ring scission polymerization conditions.
The monomer and polymer compositions of this invention provide a family of improved thermoset resins. These resins can be processed to prepare engineering materials for the electronics and aerospace industries. They possess outstanding mechanical, physical, and electrical properties, as well as good chemical resistance and thermal stability at temperatures exceeding 250.degree. C. They can also be blended or alloyed with conventional thermoset resins to prepare resins with improved properties for any industry where high performance is required.